Book Review: Our Conflicted Relationship with the Sun
Despite dermatological guidelines that decree sunlight a harmful carcinogen, Rowan Jacobsen argues in “In Defense of Sunlight” that the sun helps our skin produce many compounds vital to our health. How did science miss these benefits? The answer, he says, lies in our inability to do things in moderation..
The book In Defense of Sunlight by Nina Jablonski argues that humans have an often contradictory relationship with the Sun. While sunlight is essential for life—providing vitamin D, regulating circadian rhythms, and boosting mental health—modern society has developed a complex, sometimes fearful attitude toward it. Jablonski, a biological anthropologist at Pennsylvania State University, examines how cultural, scientific, and economic factors shape this relationship. The book highlights how misinformation, such as exaggerated fears of skin cancer, has led to widespread avoidance of sunlight, despite its proven benefits. Jablonski also critiques the sunscreen industry for promoting excessive sun avoidance, which may inadvertently harm public health by contributing to vitamin D deficiencies.
Jablonski traces the evolution of humanity's relationship with the Sun over millennia. Early humans relied on sunlight for survival, but as societies developed, cultural practices—such as clothing, architecture, and outdoor labor—began to influence sun exposure. The industrial revolution further altered this dynamic by shifting work indoors and increasing urbanization, which reduced natural sunlight exposure. The book notes that in the 20th century, scientific research on skin cancer and aging led to widespread sunscreen use, but also created a cultural narrative that framed sunlight as primarily harmful. Jablonski argues that this oversimplification ignores the Sun's vital role in human biology and well-being.
One of the book's central themes is the importance of vitamin D, which the body produces when exposed to ultraviolet (UV) radiation from sunlight. Vitamin D is crucial for bone health, immune function, and mental well-being. However, the book highlights that approximately 40% of the global population is deficient in vitamin D, a condition linked to increased risks of osteoporosis, depression, and chronic diseases. Jablonski explains that while sunscreen can block UVB rays—the type needed for vitamin D synthesis—many people apply it too liberally or avoid the Sun entirely, exacerbating deficiencies. The book suggests that balanced sun exposure, rather than complete avoidance, is key to maintaining optimal vitamin D levels.
Jablonski critiques the sunscreen industry for promoting products that may do more harm than good when used improperly. She points out that many sunscreens have a high Sun Protection Factor (SPF), which measures protection against UVB rays but often provides a false sense of security against UVA rays, which penetrate deeper into the skin and contribute to aging and cancer. The book argues that the industry's emphasis on high SPF ratings encourages people to stay in the Sun longer without reapplying, increasing overall UV exposure. Additionally, Jablonski notes that some sunscreens contain chemicals that may disrupt hormones or harm marine ecosystems, raising broader environmental concerns.
The book underscores the public health consequences of widespread sun avoidance, particularly in regions with limited sunlight, such as northern latitudes. Jablonski cites studies showing that countries with lower sunlight exposure, like the United Kingdom and Canada, have higher rates of vitamin D deficiency and related health issues. The book also discusses the economic burden of these deficiencies, including increased healthcare costs for treating conditions like osteoporosis and depression. Jablonski advocates for public health policies that promote balanced sun exposure, such as encouraging short, regular periods outdoors rather than prolonged exposure during peak UV hours.
Jablonski explores how cultural attitudes toward the Sun are shaped by factors beyond science, including media, fashion, and social norms. She notes that tanned skin, once associated with outdoor labor and lower social status, became a symbol of wealth and leisure in the 20th century. Conversely, pale skin is often idealized in some East Asian cultures as a sign of refinement. The book argues that these cultural perceptions influence behavior, such as the use of tanning beds or excessive sunscreen use, which can have unintended health consequences. Jablonski emphasizes the need for a more nuanced understanding of sunlight that balances its risks and benefits.
